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Possible MemoryError regression in Python 3.14 since alpha 6 #135028

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frenzymadness opened this issue Jun 2, 2025 · 2 comments
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Possible MemoryError regression in Python 3.14 since alpha 6 #135028

frenzymadness opened this issue Jun 2, 2025 · 2 comments
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3.14 bugs and security fixes interpreter-core (Objects, Python, Grammar, and Parser dirs) topic-parser type-bug An unexpected behavior, bug, or error

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@frenzymadness
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frenzymadness commented Jun 2, 2025 •
edited by bedevere-app bot
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Bug report

Bug description:

Running a simple piece of code:

eval("(" * 200 + ")" * 200)

raised an error like this in Python 3.8:

>>> eval("(" * 200 + ")" * 200)
s_push: parser stack overflow
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
MemoryError

It was then fixed in Python 3.9 (by the new parser, I guess) and it's now back – since 3.14 alpha 6 the error for the same code is:

>>> eval("(" * 200 + ")" * 200)
Traceback (most recent call last):
  File "<python-input-0>", line 1, in <module>
    eval("(" * 200 + ")" * 200)
    ~~~~^^^^^^^^^^^^^^^^^^^^^^^
MemoryError: Parser stack overflowed - Python source too complex to parse

I did a bisection and found commit 0142236 by @markshannon, after which we see the same error. as before

CPython versions tested on:

3.14

Operating systems tested on:

Linux

Linked PRs
@frenzymadness frenzymadness added the type-bug An unexpected behavior, bug, or error label Jun 2, 2025
@JelleZijlstra JelleZijlstra added topic-parser 3.14 bugs and security fixes labels Jun 2, 2025
@picnixz picnixz added the interpreter-core (Objects, Python, Grammar, and Parser dirs) label Jun 2, 2025
vstinner added a commit to vstinner/cpython that referenced this issue Jun 2, 2025
@vstinner
pythongh-135028: Increase parser MAXSTACK for nested parenthesis
8c328bb
@bedevere-app bedevere-app bot mentioned this issue Jun 2, 2025
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vstinner commented Jun 2, 2025

I propose #135031 to fix this issue.

vstinner added a commit that referenced this issue Jun 3, 2025
@vstinner
gh-135028: Increase parser MAXSTACK for nested parenthesis (#135031)
6e80f11
miss-islington pushed a commit to miss-islington/cpython that referenced this issue Jun 3, 2025
@vstinner @miss-islington
pythongh-135028: Increase parser MAXSTACK for nested parenthesis (pyt…
8334364 
…honGH-135031)

(cherry picked from commit 6e80f11)

Co-authored-by: Victor Stinner <vstinner@python.org>
@bedevere-app bedevere-app bot mentioned this issue Jun 3, 2025
Merged
vstinner added a commit that referenced this issue Jun 3, 2025
@miss-islington @vstinner
[3.14] gh-135028: Increase parser MAXSTACK for nested parenthesis (GH…
89df01b 
…-135031) (#135059)

gh-135028: Increase parser MAXSTACK for nested parenthesis (GH-135031)
(cherry picked from commit 6e80f11)

Co-authored-by: Victor Stinner <vstinner@python.org>
@vstinner vstinner closed this as completed Jun 5, 2025
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vstinner commented Jun 5, 2025

Fixed, thanks for your report.

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